import cv2
img=cv2.imread(r'C:\Users\Administrator\Desktop\puppy.jpg')
b=img[:,:,0]
g=img[:,:,1]
r=img[:,:,2]
m1=cv2.merge((b,g,r))
m2=cv2.merge((r,g,b))
cv2.waitKey()
cv2.destroyAllWindows()